def fun(a, b):  # 定义平方差函数，a,b

    d = a * a - b * b
    return d


x = fun(5, 4)
print(x)
print(fun(6, 2))
print(fun.__doc__)
print(abs.__doc__)


def sayBye():  # 定义
    print('I love黄金矿工')
    print("Good Bye!")


for _ in range(3):
    print(sayBye())
